GUIDELINE ON IMMUNOGENICITY ASSESSMENT OF BIOTECHNOLOGY-DERIVED THERAPEUTIC PROTEINS

EMEA/CHMP/BMWP/14327/2006 COMMITTEE FOR MEDICINAL PRODUCTS FOR HUMAN USE CHMP GUIDELINE ON IMMUNOGENICITY ASSESSMENT OF BIOTECHNOLOGY-DERIVED THERAPEUTIC PROTEINS ADOPTION BY CHMP FO

European Medicines Agency

7 Westferry Circus, Canary Wharf, London, E14 4HB, UK

London, 13 December 2007 Doc Ref EMEA/CHMP/BMWP/14327/2006

COMMITTEE FOR MEDICINAL PRODUCTS FOR HUMAN USE

(CHMP)

GUIDELINE ON IMMUNOGENICITY ASSESSMENT OF BIOTECHNOLOGY-DERIVED

THERAPEUTIC PROTEINS

ADOPTION BY CHMP FOR RELEASE FOR CONSULTATION January 2007

END OF CONSULTATION (DEADLINE FOR COMMENTS) July 2007

KEYWORDS Immunogenicity, unwanted immune response, biotechnology derived

proteins, immunogenicity risk factors, assays, clinical efficacy and safety, risk management

GUIDELINE ON IMMUNOGENICITY ASSESSMENT OF BIOTECHNOLOGY-DERIVED

THERAPEUTIC PROTEINS

TABLE OF CONTENTS

EXECUTIVE SUMMARY 3

1 INTRODUCTION 3

2 SCOPE 4

3 LEGAL BASIS 4

4 MAIN GUIDELINE TEXT 4

4.1 FACTORS THAT MAY INFLUENCE THE DEVELOPMENT OF AN IMMUNE RESPONSE AGAINST A THERAPEUTIC PROTEIN 4

4.1.1 Patient- and disease-related factors 4

4.1.2 Product related risk factors of immunogenicity 6

4.2 NON-CLINICAL ASSESSMENT OF IMMUNOGENICITY AND ITS CONSEQUENCES 7

4.3 DEVELOPMENT OF ASSAYS FOR DETECTING AND MEASURING IMMUNE RESPONSES IN HUMANS 7

4.3.1 Assay strategy 7

4.3.2 Antibody assays 7

4.3.3 Assay validation 8

4.3.4 Characterisation of antibodies to a therapeutic protein 9

4.4 POTENTIAL CLINICAL CONSEQUENCES OF IMMUNOGENICITY 10

4.4.1 Consequences on Efficacy 10

4.4.2 Consequences on Safety 10

4.5 IMMUNOGENICITY AND CLINICAL DEVELOPMENT 11

4.5.1 Rationale for sampling schedule and kinetics of the antibody response 11

4.5.2 Consequences on pharmacokinetics of the product 12

4.5.3 Methodology aspects to assess comparability of immunogenicity potential as part of a comparability exercise 12

4.5.4 Immunogenicity in paediatric indications 13

4.6 RISK MANAGEMENT PLAN 13

REFERENCES 14

ANNEX 1 FURTHER DETAILS ON METHODS FOR ASSESSMENT AND CHARACTERISATION OF IMMUNOGENICITY 15

ANNEX 2 AN EXAMPLE OF A STRATEGY FOR ANTIBODY DETECTION AND CHARACTERISATION 18

EXECUTIVE SUMMARY

The number of biological/biotechnology-derived proteins used as therapeutic agents is steadily increasing These products may induce an unwanted immune response in treated patients, which can

be influenced by various factors, including patient-/disease-related factors and product-related factors This document contains background information concerning the potential causes and impacts of immunogenicity and provides general recommendations for the performance of a systematic immunogenicity assessment from a marketing authorisation perspective

The predictive value of non-clinical studies for evaluation of immunogenicity of a biological medicinal product in humans is low due to inevitable immunogenicity of human proteins in animals While non-clinical studies aimed at predicting immunogenicity in humans are normally not required, animal models may for example be of value in evaluating the consequences of an immune response

It is essential to adopt an appropriate strategy for the development of adequate screening and confirmatory assays to measure an immune response against a therapeutic protein Assays may need to

be capable of distinguishing neutralizing from non-neutralizing antibodies, and for use in pivotal clinical trials as well as in post-authorisation studies to be validated

In the clinical setting, careful planning of immunogenicity evaluation should include data systematically collected from a sufficient number of patients For a given product, sampling should preferably be standardized across studies (e.g., sampling at baseline, under treatment and follow up samples) The sampling schedule for each product is determined on a case-by-case basis, taking into account also the risks associated with an unwanted immune response to patients Data on the impact

on efficacy and safety should be collected in order to fully understand the clinical consequences of the immune response Immunogenicity issues should be further addressed in the Risk Management Plan The scope of this guideline covers a wide applicability Thus, the concepts might have to be adapted

on a case-by-case basis to fit an individual development programme Applicants should consider the possibility to seek Scientific Advice from EMEA or from National Competent Authorities

1 INTRODUCTION

Most biological/biotechnology-derived proteins induce an unwanted immune response that is triggered

by more than one single factor This immunological response is complex and, in addition to antibody formation, other events such as T cell activation or innate immune response activation could contribute to potential adverse responses

The consequences of an immune reaction to a therapeutic protein range from transient appearance of antibodies without any clinical significance to severe life-threatening conditions Potential clinical consequences of an unwanted immune response are a loss of efficacy of the therapeutic protein, serious general immune effects such as anaphylaxis, and, for therapeutic proteins used for substitution,

a potential cross-reactivity with the endogenous counterpart in case it is still produced

Many factors may influence the immunogenicity of therapeutic proteins They can be considered to be patient-, disease- or product-related Patient-related factors that might predispose an individual to an immune response include: underlying disease, genetic background, immune status, including immunomodulating therapy, and dosing schedule Product-related factors also influence the likelihood

of an immune response, e.g the manufacturing process, formulation, and stability characteristics Although data on possible unwanted immune reactions to therapeutic proteins are required before marketing authorisation, problems may still be encountered in the post-authorisation period In the marketing authorisation application, the applicant should include a summary of investigations of immunogenicity in the respective overview sections with full cross-reference to the data in the relevant modules Depending on the immunogenic potential of the therapeutic protein and the rarity of the disease, the extent of immunogenicity data before approval might be limited Further systematic immunogenicity testing might become necessary after marketing authorization, and may be included

in the risk management plan

2 SCOPE

The general principles adopted and explained in this document mainly apply to the development of an unwanted immune response against a therapeutic protein in patients and how to systematically evaluate this The guideline applies to proteins and polypeptides, their derivatives, and products of which they are components, e.g., conjugates These proteins and polypeptides are mainly produced from recombinant or non-recombinant expression systems Throughout this guideline, the term

“therapeutic protein” is used This guideline should be read in conjunction with other relevant guidelines, e.g.:

• Guidelines on similar biological (biosimilar) medicinal products;

• Guidelines on comparability of biotechnology-derived medicinal products after a change in the manufacturing process

For coagulation factors, please, refer to the specific CHMP guidelines in this area (see references)

This guideline has to be read in conjunction with the introduction and general principles (4) and part III of the Annex I to Directive 2001/83 as amended

The consequences of an immune reaction to a therapeutic protein range from transient appearance of antibodies without any clinical significance to severe life threatening conditions As a rule, therapeutic proteins should be seen as individual products, and experience from related proteins can only be considered supportive Also in this respect, concomitant medications and other patient-related factors like the underlying disease have to be taken into account, since these can also influence the clinical presentation of immunogenicity Therefore, immunogenicity evaluation needs to be studied individually for each indication/patient population

Evaluation of immunogenicity should be a multidisciplinary task, encompassing joint efforts of quality, non-clinical and clinical experts

This document gives general recommendations and principles for developers and assessors of biotechnology-derived therapeutic proteins of how to approach immunogenicity evaluation from a marketing authorisation perspective The scope of this guideline covers a wide applicability Thus, the concepts might have to be adapted on a case-by-case basis to fit an individual development programme For the justification of their approach to immunogenicity testing, Applicants should take into consideration both the risk for developing an unwanted immune response, and the potential clinical consequences as outlined below The approach taken for the design of the immunogenicity development concept should be fully justified, e.g when omitting assays or immune response measurements proposed in this guideline Applicants should consider the possibility to seek Scientific Advice from EMEA or from National Competent Authorities

4.1 Factors that may influence the development of an immune response against a therapeutic protein

4.1.1 Patient- and disease-related factors

Patient-related factors, which might influence the immune response to a therapeutic protein, may include genetic factors, age of the patient, disease-related factors including other treatments, and previous exposure to similar proteins

• Genetic factors modulating the immune response

Genetic factors can alter the immune response to a therapeutic protein and lead to inter-patient variability Allelic polymorphism in the major histocompatibility complex (MHC), impacting on affinity and stability of the interaction between MHC molecules and antigenic peptides, and genes

encoding the T cell receptor of helper T cells may influence immune responses and immunological tolerance induction

Immune responses may occur even if the amino acid sequence of the therapeutic protein is fully human

Other genetic factors influencing immunogenicity could be gene polymorphisms for cytokines that play a role in the fine-tuning of the immune response (e.g interleukin-10, TGF-beta etc.)

• Genetic factors related to a gene defect

If the therapeutic protein is used for substitution of an endogenous protein, reduced levels or even the

lack of this protein may influence immunological tolerance, since for these patients the physiological antigen may represent a neo-antigen

The data from one age group cannot necessarily be projected to others since immune response against

a therapeutic protein can be an age-related phenomenon Children may possibly have a different immune response to these proteins If the product is indicated in children, studies on immunogenicity should be carried out in this age group (see section 4.5.4) If indicated in elderly, consideration should

be given to a potentially altered immune response

• Disease-related factors

The patient’s underlying disease itself can be an important factor in the context of developing an unwanted immune response

Some patients with chronic infections may be more prone to an immune response, since their immune system is in an activated state

In other conditions (e.g malnutrition, advanced metastatic disease, advanced HIV disease, organ failure), an immune response against a therapeutic protein might be less likely to occur due to an impaired immune system

For some products, it has been reported that the development of an antibody response can be different for different therapeutic indications or different stages of the disease Therefore, immunogenicity normally needs to be studied separately for each disease or stage of the disease as part of the clinical studies

• Concomitant treatment

Concomitant therapies may either decrease or increase the risk of an immune response to a therapeutic protein Typically, the immune reaction against a therapeutic protein is reduced when immunosuppressive agents are used concomitantly Consideration should also be given to previous treatments, that can modulate the immune reaction to a therapeutic protein and that have a long-term impact on the immune system If clinical trials are performed in combination with immunosuppressants, a claim for use of the therapeutic protein in monotherapy must be accompanied

by adequate clinical data on the immunogenicity profile in absence of immunosuppressants, i.e immunogenicity data from the combination with immunosuppressants are not relevant for the monotherapy setting

• Duration, route of administration, treatment modalities

Factors which may increase the immune response to a therapeutic protein may be the route of administration, dose, and the schedule of administration

Products given intravenously may be less immunogenic than those given subcutaneously or intramuscularly

Short-term treatment only is usually less likely to be associated with immune response than long-term treatment, and products given continuously are usually less immunogenic than those given intermittently

Intermittent treatment or re-exposure after a long treatment free interval may be associated with an enhanced immune response

• Previous exposure to similar or related proteins

Previous exposure to similar or related proteins can lead to pre-sensitisation and cause an immune response For certain proteins being used for replacement therapy, previous therapies may have induced cross-reacting antibodies or immunological memory that affects subsequent therapies

4.1.2 Product related risk factors of immunogenicity

Product-related factors influencing the immunogenicity of biological/biotechnology-derived therapeutic proteins include the origin and nature of the active substance (structural homology, post-translational modifications), modification of the native protein (e.g pegylation), product- and process-related impurities (e.g breakdown products, aggregates and host cell proteins, lipids or DNA), and formulation

• Protein structure

Biotechnology-derived analogs to human endogenous proteins may trigger an immune response due to variations in the amino acid sequence or changes to the protein structure as a result of post-translational modifications, physical, chemical or enzymatic degradation and/or modification e.g deamidation, oxidation and sulfatation during all steps of the manufacturing process and during storage Fusion proteins composed of a foreign and self-protein are of particular concern because of the potential of the foreign moiety to provoke an immune response to the self-protein (epitope-spreading) Identification of the antigenic moiety of the fusion protein is advisable Glycosylation is a frequent posttranslational modification of biotechnology-derived therapeutic proteins These modifications may differ in the number and position of glycosylation sites as well as sequence, chain length and branching of the attached oligosaccharide Therefore, when the same protein is manufactured under different conditions (e.g change in cell culture process) there might be changes in the pattern of post-translational modifications and the immunogenic potential of the protein This means also that antibodies induced by one product may react differently with the analogous product manufactured under modified conditions This might have to be considered for evaluation of immunogenicity

• Formulation

The composition of a formulation is chosen in order to best maintain the native conformation of therapeutic proteins A successful, robust formulation depends on the understanding of the physical and chemical nature of the active substance and the excipients alone and their interaction The formulation and the source of excipients may alter immunogenicty of therapeutic proteins and should

be considered as a possible cause of such events This should be considered when variations to the formulation are made

Impact of the primary packaging material and the conditions of clinical use e.g dilution in infusion solutions and infusion devices of different materials could also influence the immunogenic potential of

a therapeutic protein

• Aggregation and Adduct Formation

Aggregation or adduct formation of proteins may either reveal new epitopes or lead to the formation

of multivalent epitopes, which may stimulate the immune system Factors which could be considered

to contribute to aggregate or adduct formation include formulation, purification processes, viral inactivation procedures, and storage conditions of intermediates and finished product The use of proteins, e.g albumin, as excipient may lead to the formation of more immunogenic aggregates It is important to monitor the aggregate and adduct content of a product throughout its shelf life

• Impurities

There are a number of impurities of therapeutic proteins, which potentially can serve as adjuvants Host cell proteins (HCPs) from the cell substrate co-purified with the active substance could induce

immune responses against themselves But it is also possible that these HCPs, host cell-derived lipids

or DNA function as adjuvants for the protein of interest

4.2 Non-clinical assessment of immunogenicity and its consequences

Therapeutic proteins show species differences in most cases Thus, human proteins will be recognised

as foreign proteins by animals For this reason, the predictivity of non-clinical studies for evaluation of immunogenicity is considered low Non-clinical studies aiming at predicting immunogenicity in humans are normally not required However, ongoing consideration should be given to the use of

emerging technologies (novel in vivo, in vitro and in silico models), which might be used as tools

Measurement of antibodies in non-clinical studies are however requested as part of repeated dose toxicity studies, in order to aid in the interpretation of these studies (as discussed in “Note for guidance on preclinical safety evaluation of biotechnology-derived pharmaceuticals.” ICH S 6)

Also, the comparison of the antibody response to the reference product in an animal model may be part of the comparability exercise both for similar biological medicinal products (see Guideline on Similar biological medicinal products containing biotechnology-derived proteins as active substance: Non-clinical and clinical issues CHMP/42831/05 and product-specific annexes) and for changes in manufacturing processes (see Guideline on comparability of biotechnology-derived medicinal products after a change in the manufacturing process – Non-clinical and clinical issues CHMP/BMWP/202695/06)

An immune response to a therapeutic protein representing a counterpart to an endogenous protein may result in cross-reactivity, directed to the endogenous protein in cases where endogenous protein is still produced Any relevant experience on the consequences of induction of an immune response to the endogenous protein or its absence/dysfunction in animal models should be discussed Both humoral and cellular immune responses (where relevant) should be considered In absence of such data, and if theoretical considerations are suggestive of a safety risk, animal immunisation studies with the therapeutic protein or the animal homolog may be considered in order to gain information on the potential consequences of an unwanted immune response

4.3 Development of assays for detecting and measuring immune responses in humans

Unwanted immunogenicity induced by biologicals can comprise humoral and cellular immune responses It is therefore very important to select and/or develop assays and assay strategies for assessment of such immune responses Most effort is usually focused on antibody detection and characterisation, as this is technically feasible and often related to clinical safety and efficacy However, cell-mediated responses could play an important role and their assessment may be

considered by applicants on a case by case basis

4.3.1 Assay strategy

Adopting an appropriate strategy for assessment of unwanted immunogenicity of biological products

is essential This should usually include a screening assay for identification of antibody positive samples/patients, analytical immunochemical procedures for confirming the presence of antibodies and determining antibody specificity and functional assays for the assessment of the neutralizing capacity of antibodies In addition, non-antibody assays e.g., assays for relevant biomarkers or pharmacokinetic measurements will be required which assess and characterize the clinical impact of antibodies (and possibly other components of immune responses) if these are detected/induced It is important to include baseline data from all patients where appropriate

Annex 2 shows an example of a possible strategy for antibody detection and characterisation

4.3.2 Antibody assays

• Screening assays

A screening assay should be capable of detecting antibodies induced against the biological product in all antibody positive samples/patients This implies that detection of some false positive results is inevitable as absolute screening-assay specificity is normally unattainable and false negative results

must be avoided The desirable characteristics of screening assays are sensitivity, specificity, precision, reproducibility and robustness

• Assays for confirming the presence of antibodies

These assays are necessary for elimination of false positive samples/patients following the initial screen Various approaches can be adopted for this purpose but it is necessary to select assays taking account of the limitations and characteristics of the screening assay(s) To confirm specificity, it is not normally sufficient or appropriate to simply repeat the screening assay in its original form

• Assays for dissecting the specificity of antibodies

Assays which provide information concerning the specificity of the antibodies detected may be useful

in some cases This data contributes to confirmation of the specificity of the immune response

• Neutralization assays

Assessing the neutralizing capacity of antibodies usually requires the use of bioassays An assay must

be selected or developed which responds well to the biological product Bioassays used for measuring the potency of biological products e.g for lot release purposes can often be adapted to assess neutralising antibodies However, they frequently require refining if they are to perform optimally for measuring the neutralizing capacity of antibodies If neutralising cell-based assays are not feasible/available, competitive ligand binding assays or other alternatives may be suitable However, when these are used it must be demonstrated that they reflect neutralizing capacity/potential in an appropriate manner

4.3.3 Assay validation

Assay validation is an ongoing process throughout product development Assays used for the pivotal clinical trials need to be validated for their intended purpose Validation studies must be conducted to establish that the assays show appropriately linear, concentration dependent responses to relevant analytes as well as appropriate accuracy, precision, sensitivity, specificity and robustness For pivotal clinical trials, the use of a central laboratory to perform the assays may be helpful to avoid inter-laboratory variability In the post-approval setting, it is also important to consider inter-inter-laboratory variability

Assays must also be validated to show that matrix effects caused by reagents or substances present in samples do not adversely affect the results obtained This is normally addressed by ‘recovery’ investigations conducted by observing the effects of such substances present in the matrix on the response obtained in their absence This needs to be investigated for the full range of dilutions of samples, which are to be used in assays, and, at least in some cases, limits the dilutions, which can be validly assessed

Residual biological product present in patients’ blood can complex with induced antibody and hence reduce the amount of antibody detectable by assays This may affect assays differently, depending on the assay, assay format or type and the antibody characteristics If this occurs, it may be circumvented/resolved by using a number of approaches e.g by dissociating the immune-complexes with acid, removing excess biological by solid-phase adsorption, use of long incubation times and/or using an assay which allows sufficient sample dilution to avoid this problem Such approaches must themselves be validated for effectiveness and adopted on a case-by-case basis according to needs In some cases this problem can be overcome by appropriate spacing of the timing between administration

of product and sampling for antibody assessment i.e allowing time for the product to be cleared from the circulation before sampling However this latter approach must not significantly compromise the detection of antibodies or the treatment of the patient

• Standardisation and controls

Assays must be standardised and this requires the identification and/or development of appropriate reference materials, i.e the use of relevant biological standards and/or well characterized positive and negative controls These reagents function as critical assay reagents and are essential for assay

calibration and validation This is especially important for assays used in unwanted immunogenicity investigations/studies, as it is intimately associated with assay interpretation and with distinguishing antibody positive from antibody negative samples

4.3.4 Characterisation of antibodies to a therapeutic protein

If antibodies are detected in patients undergoing therapy, these need to be characterized to establish their clinical significance This normally involves an immunological and/or biological assessment of antibody characteristics and investigation of effects of the antibodies (or other induced immune

responses) on the product Some of this can be addressed by non antibody assays as part of in vitro

studies but it may also require clinical assessment of the patients receiving therapy

• Antibody Characteristics

If antibodies are induced in patients, serum or plasma samples need to be characterised in terms of antibody content (concentration/titre), neutralizing capacity and possibly other criteria determined on a case-by-case basis according to the biological product, the type of patients treated, the aim of the study, clinical symptoms and possibly other factors These may include antibody class and subclass (isotype), affinity, specificity The degree of characterization required may differ depending on the study purpose and stage of development of the product The assays used should be qualified for their intended purpose

Antibodies present in confirmed positive samples need to be examined for specificity for the active protein and, where applicable, distinguished from antibodies which bind to product-related and process-related components It has been shown that antibodies can be induced against all and or any of these It is also useful to screen for cross reactivity with other products based on the particular protein

as well as (if possible and relevant) its endogenous counterpart

The neutralising capacity of antibodies present in positive samples needs to be established as this often correlates with diminished clinical responses to biological product In some cases, screening neutralizing samples for cross-neutralization of other products based on the same protein and the endogenous protein is important as it may have implications for clinical efficacy and safety It should

be noted that neutralizing activity does not necessarily correlate with binding antibody content i.e samples containing significant or high amounts of binding antibodies may fail to neutralize biological activity whereas samples containing lower amounts of binding antibodies can neutralize variable (sample dependant) amounts This may depend on product, but must be determined empirically

• Immunogenicity Assessment strategy –design and interpretation

Immunogenicity studies need to be carefully and prospectively designed to ensure all essential procedures are in place before commencement of clinical assessment This includes the selection, assessment, and characterisation of assays, identification of appropriate sampling points, sample volumes and sample processing/storage and selection of statistical methods for analysis of data This applies to assays used to measure and characterise antibodies and to methods employed for assessing clinical responses to antibodies if they are induced Much of this needs to be established on a case-by-case basis, taking account of product, patients, and expected clinical parameters Such studies can provide valuable information concerning significant immunogenicity of biological products, its characteristics and potential clinical consequences They can be valuable for comparative immunogenicity studies for biosimilar products or following production/process changes introduced for established products However, unwanted immunogenity can occur at a level, which will not be detected by such studies when conducted at a pre-approval stage, due to the restricted number of patients normally available for study In view of this, it is often necessary to continue assessment of unwanted immunogenicity and its clinical significance post-approval, usually as part of pharmacovigilance surveillance In some cases, post-approval clinical studies may be needed to establish the risk associated with an unwanted immune response

For further details on methods for assessment and characterisation of immunogenicity see Annex 1

4.4 Potential clinical consequences of immunogenicity

4.4.1 Consequences on Efficacy

Factors which influence whether antibodies to a therapeutic protein will induce clinical consequences include the epitope recognised, affinity, class of the antibody, the amount of antibodies generated, and the pharmacological properties of the biotechnological medicinal product In addition, the ability of immune complexes to activate complement or be cleared may be a factor that impacts clinical outcome Usually, antibodies recognising epitopes on the therapeutic protein not linked to activity are expected to be associated with less clinical consequences However, as discussed below, such antibodies can influence pharmacokinetics and, as such, influence efficacy indirectly “Neutralising” antibodies, interfering with biological activity by binding to or near the active site, or by induction of conformational changes, can induce loss of efficacy Determination of neutralizing antibodies from confirmed positives, and the assays used, should be appropriate (see section 4.3) Most importantly, neutralizing antibody assays should be capable of detecting clinically relevant neutralizing antibodies Correlation of antibody characteristics with clinical responses requires a comparison of data generated

in assays assessing antibody responses (see above) with results generated using patients’ samples and assays designed to assess clinical responses Most of the latter are product-specific, e.g assessing expansion of leukocyte populations by colony-stimulating factors, or increased reticulocyte numbers

by erythropoietin Such assays need to be selected according to product and need In many cases, it might be difficult to identify a clinical endpoint which is sensitive enough to establish the impact on clinical outcome directly, and adoption of a surrogate measure of response may be an option, e.g

biomarkers/pharmacodynamic markers The choice of such markers should be justified In vivo

comparison of patient’s clinical responses to product before and following antibody induction can provide information on the correlation between antibody development (and antibody characteristics) and clinical responses This can be done either by intra-group analysis (response in patients before and after occurrence of antibodies), or by comparison with patients within the study who do not show an immune response

4.4.2 Consequences on Safety

Loss of efficacy and alteration of the safety profile are not necessarily linked Safety issues, like infusion-related reactions, can occur even when there is no loss of efficacy

• Acute consequences

Usually, patients who develop antibodies are more likely to show infusion-related reactions Acute infusion reactions including anaphylactic reactions may develop during (within seconds) or within a few hours following infusion Applicants should differentiate between the terms “infusion reaction” and “anaphylaxis” and carefully define which symptoms to label as “infusion-related reaction”

“Infusion reactions” usually represent symptoms occurring in a close timely relationship to an infusion and are not necessarily linked to anaphylaxis or even hypersensitivity However, acute reactions can

be true allergic, namely IgE-mediated type I reactions (anaphylactic reactions), including hypotension, bronchospasm, laryngeal or pharyngeal oedema, wheezing and/or urticaria The term “anaphylaxis” should be restricted to such situations and represents a strict contraindication to further exposure to the drug However, the majority of infusion reactions are characterized by more non-specific symptoms, for some products more frequently occurring on initial exposure and sometimes less frequent/severe reactions are observed on re-exposure An infusion might not represent a contraindication to further exposure A range of symptoms including headache, nausea, fever or chills, dizziness, flush, pruritus, and chest or back pain have been described in relation to infusions It is acknowledged that the distinction between an infusion reaction and anaphylaxis can be challenging, but nevertheless such distinction in necessary due to the different clinical consequence

Applicants should not only focus on infusion reactions and anaphylactic symptoms since the consequence of immunogenicity is product-specific and can elicit unexpected clinical symptoms